This disclosure relates to uplink timing maintenance in wireless communication systems.
Wireless communication systems can include a network of one or more base stations to communicate with one or more wireless devices such as fixed and mobile wireless communication devices, mobile phones, or laptop computers with wireless communication cards. Base stations can emit radio signals that carry data such as voice data and other data content to wireless devices. A base station can transmit a signal on a downlink (DL), to one or more wireless devices. A wireless device can transmit a signal on an uplink (UL), to one or more base stations.
The uplink signals from multiple wireless devices may go through different paths and experience different propagation delays to arrive at one base station. The base station may need to control the transmission timing of the wireless devices such that the uplink signals from multiple wireless devices are time aligned when the signals arrive at the base station. An absence of time alignment may cause significant interference to other uplink users. One of the main purposes of time alignment is to counteract different propagation delays among multiple wireless devices.